Credit Quality and the Allowance for Loan and Lease Losses - Additional Information (Details) $ in Millions	12 Months Ended
Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Financing Receivable, Allowance for Credit Losses
Mortgage loans in process of foreclosure amount	$ 107	$ 154
Financing receivable, excluding accrued interest, modified in period, amount	$ 615
Loan modification program, threshold for modification, percent of total loans and leases	0.0052
Loan modification program, loans excluded from modification program	$ 29
Unfunded commitment amounts	$ 130
Modification program option, threshold period past due	90 days
Letter of Credit
Financing Receivable, Allowance for Credit Losses
Unfunded commitment amounts		60
Line Of Credit Receivable
Financing Receivable, Allowance for Credit Losses
Unfunded commitment amounts		$ 130
Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	$ 453
Residential mortgage loans
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	$ 113
Modification program option, mortgage term	480 months
Modification program option, in-process modifications	$ 3
Consumer
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	49
Consumer \| Home equity
Financing Receivable, Allowance for Credit Losses
Financing receivable, excluding accrued interest, modified in period, amount	$ 16
Modification program option, mortgage term	360 months
Minimum \| Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Modification program option, term extension	3 months
Minimum \| Residential mortgage loans
Financing Receivable, Allowance for Credit Losses
Modification program option, trial period	3 months
Modification program option, mortgage interest payment deferral, term	6 months
Maximum \| Commercial Portfolio Segment
Financing Receivable, Allowance for Credit Losses
Modification program option, term extension	12 months
Maximum \| Residential mortgage loans
Financing Receivable, Allowance for Credit Losses
Modification program option, trial period	4 months
Modification program option, mortgage interest payment deferral, term	12 months

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

Recorded investment of consumer mortgage loan receivables secured by residential real estate properties for which formal foreclosure proceedings are in process.

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